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DynamoDB Replicated Write Request Units

0

We have a global table enabled on 2 regions. For the last 17 days cost explorer shows the following stats.

On the first region (main region): 575.000 WriteRequestUnits 612,000,000.000 ReplicatedWriteRequestUnits

On the second region(used as fallback) 0 WriteRequestUnits 180,000,000.000 ReplicatedWriteRequestUnits

How is that even possible? Point-in-time recovery Backup is enabled but still the write changes are minimal.

  • Leeroy Hannigan EXPERT
    a year ago

    Do you have TTL enabled on the tables?

  • Taxidis
    a year ago

    Yes TTL is enabled. As per AWS documentation though:

    "Amazon DynamoDB Time to Live (TTL) allows you to define a per-item timestamp to determine when an item is no longer needed. Shortly after the date and time of the specified timestamp, DynamoDB deletes the item from your table without consuming any write throughput. TTL is provided at no extra cost as a means to reduce stored data volume by retaining only the items that remain current for your workload’s needs."

    Am I missing something?

  • Leeroy Hannigan EXPERT
    a year ago

    Added as an answer

Topics
Database
Tags
DatabaseAmazon DynamoDB
Language
English
Taxidis
asked a year ago454 views
2 Answers
1
Accepted Answer

Amazon DynamoDB Time to Live (TTL) allows you to define a per-item timestamp to determine when an item is no longer needed. Shortly after the date and time of the specified timestamp, DynamoDB deletes the item from your table without consuming any write throughput. TTL is provided at no extra cost as a means to reduce stored data volume by retaining only the items that remain current for your workload’s needs

For DynamoDB Global Tables, TTL items are deleted free of charge in the source region, and then that delete is replicated to all other regions. This is the reason you see an increased rWCU consumption for your tables.

More here: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/TTL.html

"If you are using Version 2019.11.21 (Current) of global tables and you also use the Time to Live feature, DynamoDB replicates TTL deletes to all replica tables. The initial TTL delete does not consume write capacity in the region in which the TTL expiry occurs. However, the replicated TTL delete to the replica table(s) consumes a replicated write capacity unit when using provisioned capacity, or replicated write when using on-demand capacity mode, in each of the replica regions and applicable charges will apply."

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EXPERT
Leeroy Hannigan
answered a year ago
0

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/TTL.html

If you are using Version 2019.11.21 (Current) of global tables and you also use the Time to Live feature, DynamoDB replicates TTL deletes to all replica tables. The initial TTL delete does not consume write capacity in the region in which the TTL expiry occurs. However, the replicated TTL delete to the replica table(s) consumes a replicated write capacity unit when using provisioned capacity, or replicated write when using on-demand capacity mode, in each of the replica regions and applicable charges will apply.

AWS
Arjan
answered a year ago

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